Light-emitting device package structure

ABSTRACT

A light-emitting device package structure includes a leadframe, a light-emitting device disposed on the leadframe, a plurality of wires electrically connecting the leadframe and the light-emitting device, and an encapsulant covering the light-emitting device, the wires and a part of the leadframe. The encapsulant has a gas space therein, and the gas space is disposed on the light-emitting device, wherein the gas space includes at least one gas.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a light-emitting device packagestructure and a manufacturing method thereof, and more particularly, toa light-emitting device package structure with gas space and amanufacturing method thereof.

2. Description of the Prior Art

Conventional fairy lights that decorate Christmas trees are composed ofmany light bulbs, and require being uniformly disposed on the Christmastrees so as to exhibit the appearance of the Christmas trees at night.However, with the development of package technology, LEDs that have theadvantages of small size, high shock resistance, low power consumption,long lifetime, no warm up time and fast response time have graduallyreplaced the conventional light bulbs.

Referring to FIG. 1, FIG. 1 is a cross-sectional schematic diagramillustrating a light-emitting device package structure applied toChristmas trees according to the prior art. As shown in FIG. 1, thelight-emitting device package structure 10 includes a leadframe 12, alight-emitting device 14 and an encapsulant 16. The leadframe 12 has twoleads 18. The light-emitting device 14 is mounted on the leadframe 12,and an anode and a cathode of the light-emitting device 14 areelectrically connected to the leads 18 by two respective wires 20. Theencapsulant 16 is a hemispherical lens structure encapsulating thelight-emitting device 14, and a center of a cambered surface of thehemispherical lens structure disposed on the light-emitting device 14has a concavity with an upside down conoid shape. The light (indicatedby the arrow shown in FIG. 1) emitted from the light-emitting device 14can be reflected by the concavity 22 while passing though the concavity22, and then emitted to an edge of the light-emitting device packagestructure 10. Therefore, a luminous angle is increased.

Referring to FIG. 2, FIG. 2 is a schematic diagram illustrating arelation between luminous intensity and luminous angle of thelight-emitting device package structure according to the prior art. Asshown in FIG. 2, the luminous intensity of the light-emitting devicepackage structure can be detected at the luminous angle between positive90 degrees and negative 90 degrees. This means that the light-emittingdevice package structure from the optical axis to 90 degrees deviated tothe edge emits light, so that the light-emitting device packagestructure has a certain luminous intensity at the luminous angle frompositive 90 degrees to negative 90 degrees. Therefore, when thelight-emitting device package structure is disposed on the Christmastree, the Christmas lamp can be clearly viewed from all kinds of anglesbelow the Christmas tree.

Although the light-emitting device package structure according to theprior art can emit light at the luminous angle of 90 degrees, theluminous intensity at the optical axis of the light-emitting devicepackage structure is reduced by the concavity. The reduced luminousintensity is substantially at the luminous angle between positive 20degrees and negative 20 degrees. Therefore, when the light-emittingdevice package structure according to the prior art is applied to theChristmas tree, the viewing distance between the viewer and theChristmas tree is limited because of the limit of the luminous intensityof the light-emitting device package structure. To increase the luminousintensity at the optical axis of the light-emitting device packagestructure and to keep the luminous intensity at the edge of thelight-emitting device package structure are important objectives to beachieved.

SUMMARY OF THE INVENTION

It is therefore an objective of the present invention to provide alight-emitting device package structure and a manufacturing methodthereof so as to increase the viewing distance of the Christmas lamp.

According to an embodiment of the present invention, the presentinvention discloses a light-emitting device package structure. Thelight-emitting device package structure comprises a leadframe, alight-emitting device, a plurality of wires and an encapsulant. Thelight-emitting device is disposed on the leadframe, and thelight-emitting device has a main luminous surface. The wireselectrically connect the leadframe and the light-emitting device. Anencapsulant encapsulates the light-emitting device, the wires and a partof the leadframe, and an inside of the encapsulant has a gas space. Thegas space is disposed on the main luminous surface of the light-emittingdevice, and the gas space comprises at least one gas.

According to another embodiment of the present invention, the presentinvention discloses a manufacturing method of a light-emitting devicepackage structure. First, a light-emitting device structure is provided,wherein the light-emitting device structure comprises a firstencapsulated portion, and a top surface of the first encapsulatedportion has a concavity. Then, a colloid is injected into anencapsulating mold. Next, the light-emitting device structure isinserted into the encapsulating mold to form a gas space between thecolloid and the first encapsulated portion, and the colloid covers thefirst encapsulated portion. Then, a baking process is performed to makethe colloid form a second encapsulated portion outside the firstencapsulated portion and to form the light-emitting device packagestructure.

The present invention forms the gas space inside the light-emittingdevice package structure in the encapsulation process by the concavityof the light-emitting device structure. Therefore, the light emittedfrom the light-emitting device can be partially reflected by the gasspace, and the light passing through the gas space can be condensed bythe second encapsulated portion. Therefore, not only the luminousintensity of at the center of the optical axis of the light-emittingdevice package structure can be increased, but the light-emitting devicepackage structure can also have sufficient luminous intensity at theedge.

These and other objectives of the present invention will no doubt becomeobvious to those of ordinary skill in the art after reading thefollowing detailed description of the preferred embodiment that isillustrated in the various figures and drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional schematic diagram illustrating alight-emitting device package structure applied to Christmas treesaccording to the prior art.

FIG. 2 is a schematic diagram illustrating a relation between luminousintensity and luminous angle of the light-emitting device packagestructure according to the prior art.

FIG. 3 is a cross-sectional schematic diagram illustrating alight-emitting device package structure according to a first embodimentof the present invention.

FIG. 4 is a cross-sectional schematic diagram illustrating alight-emitting device package structure according to a second embodimentof the present invention.

FIG. 5 is a schematic diagram illustrating a relation between luminousintensity and luminous angle of the light-emitting device packagestructure according to the first embodiment of the present invention.

FIG. 6 is a flow chart illustrating a manufacturing method of thelight-emitting device package structure of the present invention.

FIG. 7 through FIG. 10 are schematic diagrams illustrating themanufacturing method of the light-emitting device package structureaccording to the first embodiment of the present invention.

FIG. 11 is a schematic diagram illustrating the manufacturing method ofthe light-emitting device package structure according to the secondembodiment of the present invention.

DETAILED DESCRIPTION

Referring to FIG. 3, FIG. 3 is a cross-sectional schematic diagramillustrating a light-emitting device package structure according to afirst embodiment of the present invention. As shown in FIG. 3, thelight-emitting device package structure 100 includes a leadframe 102, alight-emitting device 104, a plurality of wires 106, and an encapsulant108. The leadframe 102 of this embodiment includes two leads 110, butthe leadframe of the present invention is not limited to only have twoleads. The number of leads can be increased according to the actualrequirements. The light-emitting device 104 is disposed on one of theleads 110, and a top surface of the light-emitting device 104 is a mainluminous surface. In addition, the light-emitting device 104 can be anykind of luminous device, such as a light emitting diode (LED) chip, LEDdevice or organic LED device, etc. This embodiment takes the LED chip asan example, but this is not meant to be a limitation. Furthermore, eachwire 106 electrically connects the light-emitting device 104 and eachlead 110 respectively. The light-emitting device 104 can be suppliedwith a power source by the leads 110 so as to generate light. Inaddition, the encapsulant 108 encapsulates the light-emitting device104, the wires 106 and a part of the leadframe 102 so as to protect thelight-emitting device 104 and wires from being damaged by contact withthe outside body or dust. The encapsulant 108 is a transparent solid,and has no fluidness. The encapsulant includes at least one packagematerial, such as glass, quartz, resin with high transmittance,silicone, combinations thereof, or other suitable materials. The resinwith high transmittance includes epoxy resin, polystyrene (PS),acrylonitrile-butadene-styrene (ABS), polymethyl methacrylate (PMMA),acrylic resin or combinations thereof.

In addition, the light-emitting device package structure 100 of thisembodiment further includes a transparent shell 114 disposed inside theencapsulant 108. This means that the encapsulant 108 of this embodimentencapsulates the whole transparent shell 114, but the invention is notlimited to this. The transparent shell 114 is disposed on the mainluminous surface 112 of the light-emitting device 104. Furthermore, theinside of the transparent shell 114 has a gas space 116, and the gasspace 116 includes at least one gas, such as air. It should be notedthat the light emitted from the light-emitting device 104 can bereflected and refracted because of the difference between a refractiveindex of the transparent shell 114 and a refractive index of the gas inthe gas space 116. For this reason, the top surface and the edge of thelight-emitting device package structure 100 all emit the light. The topsurface of the encapsulant 108 is a convex surface, such as a paraboloidor spherical surface with a concave hole oriented downward, and thelight emitted from the top surface of the light-emitting device packagestructure 100 can be condensed by the convex surface to the outside.Therefore, the luminous intensity at the optical axis can be efficientlyincreased. The curvature of the convex surface is not limited to theparaboloid or the spherical surface, and the condensation can beadjusted correspondingly according to the actual requirements.

Furthermore, the transparent shell 114 is composed of transparentmaterials, such as glass, quartz, resin with high transmittance,silicone, or combinations thereof. The transparent shell 114 further canbe composed of the same material as the encapsulant 108, and thetransparent shell 114 and the encapsulant 108 can have a same refractiveindex, so that the light can regard the transparent shell 114 and theencapsulant 108 as a same dielectric, but the embodiment is not limitedto this. The transparent shell 114 of the present invention can also becomposed of materials different from the encapsulant 108 according to anactual required pattern of the light. It should be noted that refractiveindexes of the transparent shell 114 and the encapsulant 108 should belarger than a refractive index of the gas in the gas space 116. Aphenomenon of total reflection for the light at an interface between thetransparent shell 114 and the encapsulant 108 or between the transparentshell 114 and the gas space 116 can be provided to have enoughreflective light. In this embodiment, the transparent shell 114 is aspherical shell; that is, the gas space 116 disposed inside thetransparent shell 114 is spherical. When the light passes through thetransparent shell 114, a part of the light is reflected by thetransparent shell 114, and emits from the edge of the light-emittingdevice package structure 100. The light-emitting device packagestructure 100 therefore has the edge light. The other part of the lightpasses through the transparent shell 114, and passes through the topsurface of the encapsulant 108 so as to be condensed. Therefore, theluminous intensity of the light-emitting device package structure 100 atthe optical axis can be increased. The transparent shell 114 of thepresent invention is not limited to be spherical, and a surface of thetransparent shell 114 facing the light-emitting device 104 also can beconoid or a convex surface.

In this embodiment, the encapsulant 108 can include a first encapsulatedportion 118 and a second encapsulated portion 120. The firstencapsulated portion 118 encapsulates a part of the leadframe 102, thelight-emitting device 104 and the wires 106, and the second encapsulatedportion 120 covers a part of the first encapsulated portion 118. Inaddition, the transparent shell 114 is disposed between the firstencapsulated portion 118 and the second encapsulated portion 120. Itshould be noted that the first encapsulated portion 118 has a concavity122, and the concavity 122 faces the gas space 116 of the transparentshell 114. The shape of the concavity 122 can be an upside-down conoidshape, but the embodiment is not limited to this. Furthermore, the firstencapsulated portion 118 and the second encapsulated portion 120 can becomposed of same materials so as to have a same refractive index, butthe embodiment is not limited to this. The first encapsulated portion118 and the second encapsulated portion 120 of the present inventionalso can be composed of different materials, and the refractive indexesof the first encapsulated portion 118 and the second encapsulatedportion 120 are larger than the refractive index of the gas in the gasspace 116.

The light-emitting device package structure of the present invention isnot limited to the structure of the above-mentioned embodiment, and thelight-emitting device package structure of the present invention canalso have no transparent shell. In order to clearly describe thedifference between the following embodiments and the above-mentionedembodiment, devices use the same labels as the above-mentionedembodiment, and same structures will not be detailed redundantly.Referring to FIG. 4, FIG. 4 is a cross-sectional schematic diagramillustrating a light-emitting device package structure according to asecond embodiment of the present invention. As shown in FIG. 4, comparedwith the first embodiment, the light-emitting device package structure200 of this embodiment does not have the transparent shell, and the gasspace 116 of this embodiment is a bubble encapsulated by the concavity122 of the first encapsulated portion 118 and the second encapsulatedportion 120 of the encapsulant 108. The gas space 116 is disposed insidethe encapsulant 108, and is disposed on the light-emitting device 104.In addition, a shape of a side of the gas space 116 facing the firstencapsulated portion 118 is the same as the shape of the concavity, anda shape of another side of the gas space 116 facing the secondencapsulated portion 120 is a cambered surface.

In order to clearly describe the efficiency of the light-emitting devicepackage structure of the present invention, the first embodiment istaken as an example. Referring to FIG. 5, FIG. 5 is a schematic diagramillustrating a relation between luminous intensity and luminous angle ofthe light-emitting device package structure according to the firstembodiment of the present invention, and FIG. 2 is compared with FIG. 5.As shown in FIG. 5, the luminous intensity at zero degree of thelight-emitting device package structure of the present invention, whichis the luminous intensity at the optical axis, is substantially 4Watts/solid angle (W/sr). As compared with FIG. 2, the luminousintensity at zero degrees of the light-emitting device package structureof the prior art is substantially 1.1 W/sr. Therefore, the luminousintensity at the optical axis of the light-emitting device packagestructure of the present invention is larger than that of the prior art.Furthermore, the luminous intensity of the light-emitting device packagestructure of the present invention can be detected to be substantially0.15 W/sr, and is substantially the same as the luminous intensity ofthe light-emitting device package structure of the prior art, when theluminous angle is between positive 75 degrees and positive 90 degreesand between negative 75 degrees and negative 90 degrees. Therefore, thelight-emitting device package structure of the present invention notonly increases the luminous intensity at the optical axis, but alsomaintains the luminous intensity from the edge of the light-emittingdevice package structure so as to help to increase the viewing distancebetween the viewer and the Christmas lamp.

In addition, the present invention also provides a manufacturing methodof the above-mentioned light-emitting device package structure.Referring to FIG. 6, FIG. 6 is a flow chart illustrating a manufacturingmethod of the light-emitting device package structure of the presentinvention. As shown in FIG. 6, the manufacturing method of thelight-emitting device package structure comprises:

Step S10: providing a light-emitting device structure, wherein thelight-emitting device structure comprises a first encapsulated portion,and a top surface of the first encapsulated portion has a concavity;

Step S20: injecting a colloid into an encapsulating mold;

Step S30: inserting the light-emitting device structure into theencapsulating mold to form a gas space between the colloid and the firstencapsulated portion, and covering the first encapsulated portion withthe colloid; and

Step S40: performing a baking process to make the colloid form a secondencapsulated portion outside the first encapsulated portion to form thelight-emitting device package structure.

In step S10, the step of providing the light-emitting device structurecomprises:

Step S102: bonding at least one light-emitting device on a leadframe;

Step S104: electrically connecting the light-emitting device and theleadframe with a plurality of wires; and

Step S106: performing an encapsulation process to form the firstencapsulated portion encapsulating the light-emitting device, the wiresand a part of the leadframe.

In order to clearly describe the manufacturing method of thelight-emitting device package structure according to the firstembodiment of the present invention, referring to FIGS. 7 through 10 andreferring to FIG. 3 and FIG. 6, FIGS. 7 through 10 are schematicdiagrams illustrating the manufacturing method of the light-emittingdevice package structure according to the first embodiment of thepresent invention. As shown in FIG. 7, in step S102, a light-emittingdevice 104 and a leadframe 102 is provided, and then, a die bondingprocess is performed to bond the light-emitting device 104 on theleadframe 102. Next, a wire bonding process is performed to electricallyconnect the light-emitting device 104 and the leadframe 102 with thewires 106.

Thereafter, as shown in FIG. 8, in step S106, an encapsulation processis performed to form a first encapsulated portion 118 to encapsulate thelight-emitting device 104, the wires 106 and a part of the leadframe102, and then, a light-emitting device structure 150 is completed. A topsurface of the first encapsulated portion 118 has at least one concavity122. It should be noted that the light-emitting device structure 150 ofthis embodiment is a structure having a light-emitting device 104 and afirst encapsulated portion 118. The light-emitting device structure 150of the present invention can also be a semi-manufacturing product havinga plurality of light-emitting devices encapsulated by the firstencapsulated portion, and the light-emitting devices are disposed on theleadframe. Additionally, the light-emitting device structure 150 can bean edge lighting LED.

Then, as shown in FIG. 9, a transparent shell 114 is bonded on theconcavity 122 of the light-emitting device structure 150. The gas space116 is inside the transparent shell 114, and is disposed on the mainluminous surface 112 of the light-emitting device 104.

Next, as shown in FIG. 10, in step S20, another encapsulation process isperformed to inject the colloid 152 into the encapsulating mold 154. Instep S30, the light-emitting device structure 150 having the transparentshell 114 is disposed upside down, and is inserted to the colloid 152 inthe encapsulating mold 154 so as to form the gas space 116 between thecolloid 152 and the light-emitting device structure 150. The colloid 152covers the transparent shell 114 and the first encapsulated portion 118of the light-emitting device structure 150. In this embodiment, thetransparent shell 114 is bonded on the concavity of the light-emittingdevice structure 150 between step S10 and step S20, so that the gasspace 116 inside the transparent shell 114 can be formed between thecolloid 152 and the light-emitting device structure 150.

Then, in step S40, a baking process is performed to form the secondencapsulated portion 120 on the light-emitting device structure 150 withthe colloid 152. Finally, the encapsulating mold 154 is removed to formthe light-emitting device package structure 100 of the first embodimentshown in FIG. 3. The manufacturing method of the light-emitting devicepackage structure of the present invention is not limited to onlymanufacturing a single light-emitting device package structure, and canalso manufacture a plurality of the light-emitting device packagestructures at a time. While manufacturing the light-emitting devicepackage structures, the manufacturing method further comprises a cuttingprocess after the step of removing the encapsulating mold, and thecutting process is performed to form a single light-emitting devicepackage structure.

The present invention further provides a manufacturing method of thelight-emitting device package structure of the second embodiment.Referring to FIG. 11 and referring to FIGS. 6 through 8, FIG. 10 andFIG. 4, FIG. 11 is schematic diagram illustrating the manufacturingmethod of the light-emitting device package structure according to thesecond embodiment of the present invention. As shown in FIGS. 6 through8, compared with the manufacturing method of the first embodiment, thesteps for forming the light-emitting device structure of themanufacturing method of this embodiment are the same as step S10 of themethod of the first embodiment, and will not be detailed redundantly.Next, as shown in FIG. 10, in step S20, the encapsulation process isperformed to inject a colloid 152 into an encapsulating mold 154, andthen, in step S30, the light-emitting device structure 150 having theconcavity 122 is disposed upside down and directly inserted into thecolloid 152 in the encapsulating mold 154. The difference between themethod for forming the gas space 116 of the first embodiment and themethod of this embodiment is that this embodiment uses the concavity 122of the first encapsulated portion 118 to reserve air in the concavity122 during inserting the light-emitting device structure 150 into thecolloid 152, and the gas space 116 can be formed between the colloid 152and the light-emitting device structure 150. The gas space 116 of thisembodiment is a bubble including air. Finally, in step S40, a bakingprocess is performed to form the second encapsulated portion 120 outsidethe light-emitting device structure 150 with the colloid 152. Then, theencapsulating mold 154 is removed to form the light-emitting devicepackage structure 200 of the second embodiment shown in FIG. 4.

As mentioned above, the present invention uses a two-step encapsulationprocess to form the gas space inside the light-emitting device packagestructure. The light emitted from the light-emitting device directlyunder the gas space can pass through the gas space, and a part of thelight can be reflected to emit in the direction deviating from theoptical axis by 90 degrees. In addition, the present invention providesthe convex surface to be the top surface of the package structure. Forthis reason, the light passing through the gas space can be condensed,and the luminous intensity at the center of the optical axis of thelight-emitting device package structure can be increased accordingly.Therefore, the present invention not only can increase the luminousintensity at the center of the optical axis of the light-emitting devicepackage structure, but can also provide sufficient luminous intensity atthe edge of the light-emitting device package structure so as to solvethe problem of insufficient luminous intensity of the light-emittingdevice package structure of the prior art.

Those skilled in the art will readily observe that numerousmodifications and alterations of the device and method may be made whileretaining the teachings of the invention.

1. A light-emitting device package structure, comprising: a leadframe; alight-emitting device, disposed on the leadframe, and having a mainluminous surface; a plurality of wires, electrically connecting theleadframe and the light-emitting device; and an encapsulant,encapsulating the light-emitting device, the wires and a part of theleadframe, an inside of the encapsulant having a gas space, the gasspace being disposed on the main luminous surface of the light-emittingdevice, and the gas space comprising at least one gas, wherein theencapsulant comprises a first encapsulated portion and a secondencapsulated portion, the second encapsulated portion covering a part ofthe first encapsulated portion, and the gas space is disposed betweenthe first encapsulated portion and the second encapsulated portion. 2.The light-emitting device package structure of claim 1, furthercomprising a transparent shell, disposed between the first encapsulatedportion and the second encapsulated portion, and the gas space beingdisposed inside the transparent shell.
 3. The light-emitting devicepackage structure of claim 2, wherein a refractive index of thetransparent shell is the same as a refractive index of the encapsulant.4. The light-emitting device package structure of claim 2, wherein thetransparent shell is a spherical shell.
 5. The light-emitting devicepackage structure of claim 1, wherein the gas comprises air.
 6. Thelight-emitting device package structure of claim 1, wherein the firstencapsulated portion has a concavity, and the concavity faces the gasspace.
 7. The light-emitting device package structure of claim 6,wherein a shape of the concavity is an upside down conoid shape.
 8. Thelight-emitting device package structure of claim 1, wherein a refractiveindex of the encapsulant is larger than a refractive index of the gas.9. The light-emitting device package structure of claim 1, wherein thefirst encapsulated portion and the second encapsulated portion have asame refractive index.
 10. The light-emitting device package structureof claim 1, wherein a top surface of the encapsulant is a convexsurface.
 11. The light-emitting device package structure of claim 1,wherein the encapsulant comprises at least one encapsulating material.